Adhesive wear occurs when two solids are in a sliding contact and the atomic bonding forces occurring between the materials on the interface are stronger than the strength of the surrounding area in either of the materials . In this case, shear starts in the weakest material and the fragment of a surface is detached from one body and transferred to another. Once the fragment is transferred to another surface due to high bonding strength on the interface it may remain at the surface and form a ‘transfer film’, or a loose wear particle may form. The formation of a latter is possible due to variation of stress acting on a fragment. Inside of the contact, the fragment is under mechanical influence: heavily stressed and elastically deformed. Once the fragment leaves the contact zone, the stresses are relieved and if the relief in stress is stronger than the adhesive bonds, then the loose particle forms. Adhesive wear coefficients of metals are between depending on operational conditions and material properties.
See the results of molecular dynamic simulation of two asperities colliding with adhesive transfer of the materials:
 Yamamoto T, Buckley, D.H. Wear Mechanism Based on Adhesion, NASA Thechnical Paper 2037. Cleveland: NASA; 1982.