Wells has been sidelined with a strained right forearm since April 5.
Andrew Cashner, on the disabled list since April 6 with a strained right rotator cuff, threw two innings in live batting practice in Mesa. He was to throw on the side Friday and then the team would determine the next step in his rehab.
The Cubs' Double-A Tennessee team also announced Minor League outfielder Brett Jackson, the team's No. 1 Draft pick in 2009, was going on the disabled list with a strained ligament in his left little finger.