A jet pump body comprises nozzle and mixing chamber with diffuser, coaxially arranged, and a stepped through channel, tapers downward and provided with a seat between steps. The channel is made coaxially with a pipe string. Channels provided with return valve and restrictor for limiting locking member displacement of the return valve upward respective to the seat. A hollow stepped sealing unit with sealing element can be arranged in the through channel. An axial channel is made in the sealing element. A guiding separation bushing cantilever fitted by the top end thereof to the top part of the body of the pump mounts above the channel axially thereto in the pump body. Longitudinal slotted orifices are made in the separation bushing wall.