Moving towards high power density, high dynamic responsibility, and high reliability, the electro-hydrostatic actuators (EHA) have put forward great demand on the piston pumps. As a typical pump control system, EHA pumps need to maintain high efficiency in a wide range of rotational speed and pressure to implement the function of position servo. High speed and wide speed range bring great challenge to the cylinder block/valve plate interface, which has to fulfill simultaneously a bearing and sealing function. Cermet coatings are beneficial to improve the friction and wear performance of the sliding surfaces. In this study, a dedicated frictional test apparatus of cylinder block/valve plate interface has been built which could accurately simulate the working conditions of EHA pumps in a wide operational condition. Equations of the friction coefficient are established based on the combination of experiments and friction theory. When pairing with the tin-bronze cylinder block, friction coefficients of TiAlN coated and nitrided valve plate are calculated by these equations. Additionally, the wear status of these two friction pairs are evaluated by a 3D measuring laser microscope. In the wide speed range of 500–10000 rpm, the decrease percentage of friction coefficient and the wear rate for TiAlN coated valve plate are 52.55%–64.9% and 12–14% of the nitrided one, respectively.