Every material surface experiences wear during mechanical contact. Wear comes in different, i.e. adhesive, abrasive, fretting, corrosive, etc. form. Despite a long history of inquiries into the subject, mechanisms of wear are poorly understood. Our recent numerical development enabled a direct modeling of material removal processes, paving the way for fundamental investigations of wear mechanisms. Specifically, this research try to understand the physical origins of empirically-observed engineering wear relations and developed new mechanistic-based wear models. The long-standing quest for physics-based simulations of wear debris formation has been recently addressed through a coarse-grained atomistic approach. These simulations demonstrated two adhesive wear mechanisms: gradual asperity smoothening by plastic deformation versus fracture-induced debris formation. Examining a range of simulation parameters, we found that the size of the asperity contact junction and the strength of the adhesive bond dictate the adhesive wear mechanism. Ultimately, hard/brittle materials with large asperities and strong adhesive bonding at the asperity contact junctions favour the debris formation mechanism over the asperity smoothening mechanism.