I had a similiar problem getting the pump down a hole. Finally I saw it hanging up on a lip in the pipe on a coupler in the casing. I think I stuck a cottage cheese container on the pump bottom to slide past the ledge. This little lip even caused the bottom of the pump to be dented quite seriously.
Try screwing - turning the whole assembly when you hit the obstruction. Be patient and do it repeatedly and likely it will pass. Sort of "vibrate" the pipe at the problem area.
But if you are in an area of a rock shift or loose gravel, then you might never solve the problem.
Be sure that the wires are being pulled in concert with the pump.