Aiming to study the different diffusion regimes between uniform and non-uniform particles, Episodic Langevin Equation (ELE) based on stochastic-mechanics model was developed, which could reproduce the episodic movement (start and stop) of bed load particles, moreover, the model could link the probability distribution of velocities to the forces exerted on one single particle. We incorporated heterogeneity of particle sizes and simulated power-law distributed waiting times. For the violation of independent and identical distribution assumption, non-uniform particles resulted in completely different diffusion regimes with uniform particles. Our results demonstrate that heterogeneity in particles results in ballistic in large scales, which illustrates that the transport process is deterministic sorting, rather than anomalous diffusion.