An electrically charged particle has an electric field centred around itself that extends far into space. That field has an energy density proportional to the electric field squared. By Einstein's E=mc^2 that energy density is equivalent to a mass density. Thus, as a charged particle moves, it carries around with itself a "cloud" of mass in its electric field. If we assume the particle has a finite radius then the total mass in its electric field is finite. The centre of mass of this field mass/energy is located at the particle's postion and so moves with it. My question is this: Does this electromagnetic mass affect the particle's dynamics in exactly the same way as its "regular" mass even though it is spread diffusely throughout space? Thus is it true to say that: mass of charged particle = regular mass (localized at the particle position) + electromagnetic mass (extended throughout space)?