to be replaced the plunger is relocated to another unused barrel in the well surprisingly the barrels that are not in use do not exhibit wear during pump operation in this manner a worn barrel can be replaced with another barrel without the need to pull the tubing string from the well this replacing a worn barrel in a tubing pump can occur in a shorter time the plunger can be replaced by pulling the sucker rods and plunger the tubing need not be pulled to replace the plunger in fig1 there is shown a schematic diagram of a producing oil well 11 the well has a borehole that extends from the surface 13 into the earth past an oil bearing formation 15 the borehole has been completed and therefore has casing 17 which is perforated at the formation a packer or other method not shown optionally isolates the formation 15 from the rest of the borehole tubing 19 extends inside of the casing from the formation 15 to the surface 13 a subsurface pump 21 is located in the tubing 19 at or near the formation 15 a string of sucker rods 23 extends from the pump 21 up inside of the tubing 19 to a polished.