New application areas such as compact drives and displacement control using variable electric motors require that hydrostatic machines exhibit good performance also at very low relative speeds without being damaged during critical mixed friction conditions. While some pumps currently address this issue using leaded metals in their sliding bearings, European regulations (Reach Regulation) mandate the transition to lead-free materials in the near future. To address these challenges, this paper investigates about surface structures that offer the ability to selectively modify the pressure field within the fluid gap, generating additional hydrodynamic pressure. In this research project, various slipper surface structures of an axial piston pump were developed through extensive simulation studies and tested on a pump test-rig as well as on a dedicated hydrostatic tribometer. This paper outlines the development, construction, and optimization of a novel hydrostatic tribometer capable of adjusting speed, pressure, acceleration and temperature. Multiple measurements were conducted with different slipper geometries. The results encompass torque, temperature and wear measurements. They are presented along with a comprehensive analysis and validation of the findings in comparison to simulation and pump test results. In this study the tribometer revealed specific constraints not detected in pump bench tests, underscoring the imperative nature of such examinations.