I think there is a pretty good chance that you are looking for <PERSON> 1996 novel Reclamation.
The story is mainly told from the perspective of three characters. Two are natives of the special planet. One who comes from a high caste ('hand's rather than 'pusher's), has been abroad for a long time, and has established himself as a independent person providing specialized computer and network skills, and the other who comes form the lowest caste and has recently been kidnapped from her homeworld. The third POV character is a member of the Rhudolant Vitae (a space-going humanoid race seeking to reclaim their lost home-world) and serves as the face of the main opponents of the other two.
The male native is hired to do an ill-specified job for the Rhudolant Vitae; a job that turns out to be interacting with the female native whom they are holding captive.
Instead he breaks her out of their custody making some use of his super-normal powers along the way. 322
They separate not long after their successful escape, but not before he guides her through a painful process of overcoming the crippling agoraphobia that seems to be common to their race. Much of the book is spent on his (ultimately unsuccessful) attempts to recover the smooth running of his life after this event and on her continuing efforts to stay out of her captors hands.
Fate brings them all back to the native's world in time, and eventually the natives discover installations of great power and combine their talents1 to employ them to drive back an invasion by the Rhudolant Vitae.
The story ends with a powerfully implied spoiler
! That the native planet is the remains of Earth and the remaining habitable parts are the deepest of undersea trenches, now exposed.
The book is a fun and re-readable space operatic romp. Not deep or hugely original, but entertaining.
1 The details of their talents are another spoiler
! His talent is the ability to manipulate things, and his caste is described as 'Hand's—a reasonable match for the OP's rememberance of 'push'ing. Her talent is to interface between the machinery and other talents—you may recall that she carried special stones with her and could use them to improve her cognitive recall and organization. 999