Stewart, the 18-year-old winger from Nelson Bay, and Waratahs teammate Katrina Barker are part of a 45-player train-on squad vying for selection in the Wallaroos side to take on Japan in the first test at Newcastle's No.2 Sportsground on July 13.

Both locals were apart of the NSW side which beat Queensland 8-5 in the Super-W final on April 7.

Barker, 26, was a member of the Wallaroos squad which finished sixth at the 2017 World Cup and made her international debut the season before against England.

Stewart, a former beach sprinter and Australian touch footy representative, has been playing rugby less than two years and is coming off her maiden first Super-W campaign.

"Maya has so much raw talent," Nestor said. "For her it is about learning and understanding the game more. Especially as an outside back, in terms of positional play, that is a big thing for her.

"She has been on a pretty steep learning curve. She has genuine pace and when she learns to use that well, she will be really effective. She has a ton a potential."

As well as playing in the Newcastle competition for the Waratahs, Stewart and Barker have been travelling to Sydney to train with the other NSW players in the squad.

"They are doing gym work as well as on-field conditioning and a skill component," Nestor said. "There is a lot of learning involved in it. NSW has 14 in the group so they can do some decent work.

"Playing the game is the most important thing. If they have to make the choice between playing a game in Newcastle or attending a training session in Sydney, I say play the game. That is one of the best learning environments. Clubland has a certain level of player and you have to take that into account. It is still rugby."

Barker played halfback at the last World Cup but was used predominantly at inside centre for the NSW Waratahs last season.

"Cheech (Barker) is so versatile that she doesn't get recognised as a specialist," Nestor said. "I like the idea of her as an evasive, ball-playing centre and she has that ability. We just have to develop her game in that respect.

"At the last World Cup I enjoyed working with her as a nine. The thing about Cheech is she is tough and a real fighter. I love that characteristic about her. She will give absolutely everything. There are no gray areas. She gives everything. You would love to be able to bottle her attitude and give it to every player."

Nestor will select a squad of up to 30 players for a week-long training camp in Newcastle before the Japan Test.

"I was excited when told we would be based in Newcastle," he said. "It's such a down to earth, hard working, good Aussie place. It is perfect for us to create the environment we want to create within the girls. I love the fact that we are there."

The Wallaroos will stay in Newcastle until July 16 before moving to Sydney for the second test at North Sydney Oval on July 19.