The problem of evaluating the working period of different sliding-friction pairs is of great importance nowadays. However, there is still no exact wear calculation model that could be applied to all cases of wear processes because of difficulties connected with a variety of parameters involved in the wear process. One of the wear calculation methods is dealing with the calculation of rough surface peaks that make contact between two surfaces. Taking into account the number of these peaks and applying the fatigue wear model to them in case of sliding-friction movement it is possible to make the wear calculation of fitting under definite working conditions. The wear model is based on 3D surface micro-topography, assessing the material's physical and mechanical characteristic quantities and considering definite service conditions of sliding friction pairs.