The diffusion model is applied to extragalactic radio source extended components for modelling of radio source component images. It is assumed that the radio source hot spots (injection regions) are sources of relativistic electron plasma (accelerated by shocks). Electrons of plasma propagate due to the diffusion, lose the energy because of the synchrotron emission, and form the lobes (radio emitting clouds). The motions of the injection regions are introduced and it naturally explains the lobes size asymmetry and the displacement of the hot spots with respect to the center of the lobes [8]. There is the kinetic equation to be considered. The kinetic equation describes the diffusion of plasma relativistic electrons analytically and synchrotron losses are taken into account. The injection spectrum of the hot spots is taken as the power-law dependence on the energy within the given energy interval, the diffusion coefficient and the magnetic field are assumed to be dependent on coordinates. From the transfer equation the radio emission of electrons is found numerically, the reabsorption being taken into account. The Stoks parameters for plasma electrons are found from the formulas for the synchrotron emission. Velocities of the radio source hot spots and the diffusion velocity of plasma electrons determine the correlation of transverse and longitudinal lobe sizes. Observed changes of lobes at various frequencies accord with the diffusion model [3]. The reabsorption in the lobes leads to their asymmetry, depending on source rotation relative to the line of sight [6]. The distributions on a source of the polarized emission intensity, radio images at various frequencies and sources' spectra are received. The results are compared with the centimeter and decameter wavelengths observational data.