Low energy collisions of very heavy nuclei (238 U +238 U , 232 Th +250 Cf and 238 U +248 Cm ) have been studied within the realistic dynamical model based on multi-dimensional Langevin equations. Large charge and mass transfer was found due to the "inverse quasi-fission" process leading to formation of survived superheavy long-lived neutron-rich nuclei. In many events lifetime of the composite system consisting of two touching nuclei turns out to be rather long; sufficient for spontaneous positron formation from super-strong electric field, a fundamental QED process.