The erosion rate and surface roughness in erosion processes scale with the impact energy of the particles. The particle size and velocity distributions are therefore important parameters for a simulation model. A Monte Carlo simulation model has been developed to predict the erosion rate and surface roughness as a function of material properties of the target and of the abrasive particles. The description of the interaction between particle and substrate is based on indentation fracture mechanics. The results have been checked for the applicability to real-life abrasive jet machining. The erosion rate compares favourably with the erosion rate observed during erosion experiments on glass. The surface roughness, however, is larger then the experimental surface roughness. Probably, this can be attributed to the influence of the stylus radius on the surface roughness. The simulation model is a useful tool to study parameter variations in erosion processes of brittle materials. Various extensions to the model are possible to refine the model. With a few modifications, the model is expected to be suitable for simulation of three-body abrasion as well.