Disclosed is a bearing unit which can be used in a drainage pump operated without supply of clean water or a hydraulic pump, which exhibits excellent wear resistance against water containing earth and sand and satisfactory assembling facility, and a method of manufacturing the bearing unit.The contact surface of a bearing made of stainless steel and/or that of a sleeve is applied with a sprayed coating, the main component of which is WC, and which contains one or more elements selected from a group consisting of nickel, chromium and cobalt as a binder material thereof, or a sprayed coating, the main component of which is Cr.sub.3 C.sub.2, and which contains NiCr as a binder material, after the sprayed coating has been formed, heating at from 300.degree. C. to 550.degree. C. is performed for one hour or longer so that hardness and wear resistance equivalent to those of a WC - 12% sintered article is attained.