A cartridge assembly for use in conjunction with a linear motion guided screw assembly includes (a) a cylindrical housing having an axial bore, at least a portion of the bore being defined by a threaded surface configured to engage a screw shaft; (b) at least one bearing disposed in the axial bore of the housing; (c) at least one retainer ring disposed in the axial bore of the housing; and, (d) a cylindrical lubricant block disposed in the axial bore of the housing, the lubricant block being fabricated from a microporous polymer which is impregnated with a lubricant oil.