An oil well pumping apparatus for pumping oil from a well to a wellhead provides a tool body that is sized and shaped to be lowered into the production tubing string of the oil well. A working fluid is provided that can be pumped into the production tubing. A prime mover is provided for pumping the working fluid. A flow channel into the well bore enables the working fluid to be circulated from the prime mover via the production tubing to the tool body at a location in the well and then back to the wellhead area. A pumping mechanism is provided on the tool body, the pumping mechanism including first and second gerotors. The first gerotor is driven by the working fluid. The second gerotor is rotated by the first gerotor. The two gerotors are connected with a common shaft. The tool body has flow conveying portions that mix the working fluid and the produced oil as the oil is pumped. The pumping mechanism transmits the commingled fluid of oil and working fluid to the wellhead area where they are separated and the working fluid recycled.