In this paper, a new model is proposed for system degradation evaluation under sliding wear failure mechanism. This model estimates the material loss with respect to progression of sliding distance. This model is generated by considering physical and geometrical aspects of the system which is under wear failure mechanism. Several sets of experimental data are used for validation of the presented model. These experimental data are related to the pin-on-disk test including initially conformal and nonconformal contacts. A dataset of the pin-on-disk test by ASTM-G99 standard is used for additional model validation. The rail system data are employed for validation of the model in the practical systems. Uncertainty is analyzed by Monte Carlo simulation to determine the variations of the predicted material loss. Finally, the reliability assessment of these systems is performed.