Cashner, sidelined since April 6 with a strained right rotator cuff, threw 20 pitches, while Wells, out since April 5 with a strained right forearm, threw 15.
"I threw really well today and had a lot better command than I thought I would," Cashner said. "I threw great, everything's good and threw fastball, changeup and I'm looking forward to getting back up there.
"For me, it's just getting back in the groove of things and getting back on the mound. I've been stretching it out and it's been feeling good."
The next step will be another bullpen session on Wednesday and then Cashner will report to Arizona to face hitters at extended spring training.
Because of off-days, the Cubs don't need a fifth starter after Monday until May 14. One option could be veteran Doug Davis, who signed a Minor League contract with the team. He was scheduled to start Thursday for Class A Daytona in Tampa. Todd Wellemeyer, bothered this spring by a sore right hip, could pitch Thursday for Triple-A Iowa.