An assembly for pumping groundwater from a bore of a well includes a pump having a pump inlet positioned in the bore of the well and a screen having a plurality of apertures and positioned to surround the pump inlet. A gravel pack is inserted between the screen and native groundwater bearing formations. The gravel pack can be removed and replaced by inserting a removable slide tube down the bore of the well to hold back infall of rock or gravel debris. After replacement of the gravel pack, the slide tube is removed.