A downhole pump flushing system has a pump body defining an interior cavity, an inlet end, an outlet end and at least one flushing inlet. A lifting member is positioned within the interior cavity of the pump body for facilitating lifting of wellbore fluid. An injection mandrel in circumferentially engaging relation to an exterior surface of the pump body is provided such that it encompasses the at least one flushing inlet. The injection mandrel has an injection port fluidly connected to a fluid outlet port. The fluid outlet port is in fluid communication with the at least one flushing inlet of the pump body. An injection line is connected to the injection port of the injection mandrel and to a fluid supply. An annular channel is provided between the pump body and the injection mandrel adjacent to the at least one flushing inlet such that fluid is guided into the at least one flushing inlet from the fluid outlet port of the injection mandrel. A first sealing member and a second sealing member are provided in sealing engagement between the pump body and the injection mandrel such that a fluid tight seal is created above and below the at least one flushing inlet.