Pressel, 31, and Lewis 34, boast a combined 35 Solheim Cup matches between them, adding experience to a 12-player squad that includes five rookies.
"I just felt like I needed some veteran leadership," Inkster said of her wild-card selections. "I have a very young and inexperienced team and I needed some better balance on that.
"A lot of my players wanted Morgan and Stacy on the team, and that just kind of helped me out. And I can put each of them with anybody. With what we are trying to do team-wise, Morgan and Stacy were just perfect fits."
The USA take on Europea at the PGA Centenary Course at Gleneagles, Scotland from September 13-15.
The American squad is aiming to capture the title for a third consecutive time under Inkster.
Pressel played in five straight Solheim Cups between 2007 and 2015, building a record of 10 wins, seven losses and two ties.
She reminded Inkster of her big-match temperament this season after a fourth place finish at the Women's British Open this month.
Lewis has played in the last four Solheim Cups, winning five games, losing 10 and halving one.
"I'm pumped," said Lewis, a 12-time winner on the LPGA Tour. "I love Solheim Cup and I'm excited with the team we have this year and the rookies. I'm just excited to be the veteran and kind of help get those girls around and kind of help them get ready for what they are going to experience.
"I think a lot of the reason why I was picked was for that. Hopefully some of my experiences can bleed off on them."