tubing string but it is recognized that the continuous tubing string may be replaced by a sucker rod string with a hollow terminal portion a coupler 302 connects the pump body 112 to the production tubing 114 the pump body 112 includes an outer shell 304 a pump barrel 306 and an end cap 310 a seal 312 prevents fluid leakage between the pump barrel 306 and end cap 310 outer shell 304 is preferably a threaded cylinder concentric with the pump barrel 306 the complete pump configuration includes a pump plunger 318 coupled to the lower end of continuous tubing 118 or to the lower end of short tubing section 215 a check valve 322 is movably mounted on the continuous tubing 118 above the plunger 318 between the check valve 322 and the continuous tubing string 118 is a sealing layer that allows axial motion but prevents fluids from passing between the valve and continuous tubing string when the plunger 318 is lowered into the pump barrel 306 the check valve 322 preferably rests on a valve seat 323 formed by coupler 302 the contact surfaces of the check valve 322 and coupler 302 may be conical or spherical sections loosely mounted on the continuous tubing 118 above the check valve 322 is a centralizer 324.