The paper analyzes the features of solid particle erosion and their effect on the erosion resistance of metals. The analysis is based on the structural-temporal concept of fracture and its incubation time criterion allowing one to estimate the threshold velocity of particles versus their radius. Such dependences of the velocity threshold are presented for AMg6 aluminum and VT1-0 titanium alloys tested for drop weight impact and erosion by corundum (grit F120) particles with a velocity of up to 146 m/s. The surface of the alloys eroded at different particle velocities is examined by scanning electron microscopy, and their fracture features on scales lower than those of ordinary tensile fracture are identified.