Adepts feel pretty gimped on Insanity after having played through with Infiltrator and Soldier. Your strength is in your powers, which is to say, your strength is nonexistent 'til you've whittled down their barriers/shields far enough to actually use your powers. Given that you start with the two worst weapon types, that's a bit of a chore at least until you learn to use a third.
That said, Shockwave spam is incredibly fun versus husks and anything else that tends to bunch up. But you can do that and still generally be more effective on a Vanguard, which essentially makes Adept the redheaded stepchild of the bunch.
Whenever possible, try to set up corridors of death - things like doorways and other cramped spaces the enemy must pass through to reach you, with yourself and an ally on either side of the doorway, able to spray death at them as they approach and return to cover when necessary. Much easier than having to deal with enemies coming at you from all sides.
That said, Shockwave spam is incredibly fun versus husks and anything else that tends to bunch up. But you can do that and still generally be more effective on a Vanguard, which essentially makes Adept the redheaded stepchild of the bunch.
Whenever possible, try to set up corridors of death - things like doorways and other cramped spaces the enemy must pass through to reach you, with yourself and an ally on either side of the doorway, able to spray death at them as they approach and return to cover when necessary. Much easier than having to deal with enemies coming at you from all sides.