A sliding sleeve opens with a deployed ball and applied pressure and is subjected to reverse flow pressure. The sleeve has a housing and an insert. The housing defines a first bore and defines a flow port communicating the first bore outside the housing. The insert is disposed in the first bore of the housing and has a seat held in a first direction therein. The seat engages the deployed plug in the first direction, and the insert moves, by the applied pressure against the plug engaged in the seat, axially in the first direction inside the first bore from a closed position toward an opened position relative to the flow port. The seat is disengageable from the insert in a second direction opposite to the first direction by the reverse flow and is passable at least out of the insert.