The object of research is a tribo-fatigue shaft-insert system, where the insert is made of MONICA structural material. The purpose of this work is to analyze the stress-strain state under different loading scenarios and to evaluate potentially hazardous volumes of the material. Method. The stress-strain state of the system is evaluated using finite element modeling techniques. The three-dimensional FE model includes a description of the contact interaction between shaft and insert and realizes four different loading modes: contact load, bending load, and their combinations at different bending force direction. Results. As a result of numerical modeling the maximum stresses diverge from the analytical estimates by no more than 11.3%. During the study of the stress-strain state of the system with an insert made of MONICA material, the maximum stresses and their localization were determined, and the “dangerous” volumes were estimated. It was found that the direction of the bending force significantly affects the stress distribution and the size of dangerous zones: their relative volume can reach several percent of the part volume. The obtained dependences can be used to predict the durability of tribo-fatigue systems.