A downhole hydraulic pump apparatus for a well assembly including a rigid, elongated production tubing extending into a formation producing production fluid. The hydraulic pump apparatus includes an elongated tube and a bottom-hole assembly mounted to a lower end of the elongated tube. The bottom-hole assembly includes an upper assembly connected to a middle assembly connected to a lower assembly. The upper assembly has an upper bore therethrough. The middle assembly has a middle longitudinal bore therethrough, a fluid longitudinal port therethrough and a discharge port. The lower assembly has a lower bore and a safety valve therein. A pump assembly is formed for sliding receipt in the elongated tube. The pump assembly includes an upper pump body formed for sliding receipt in the upper assembly and a lower extension assembly connected to the upper pump body. The lower extension assembly has a first portion and a second portion. The first portion is formed to open the safety valve upon the seating of the pump assembly in the bottom-hole assembly. The second portion has an extension discharge port formed to be in fluid communication with the discharge port of the middle assembly upon the seating of the pump assembly in the bottom-hole assembly.