LONDON (Reuters) - Italian insurer Assicurazioni Generali has held talks with U.S. rival MetLife Inc to buy the bulk of its European assets but discussions have stalled due to differences over price, four sources told Reuters.Generali, which ranks as Europe's third biggest insurer, first approached MetLife earlier this year offering to take on most of its underperforming European business whose adjusted earnings slipped 4% in the third quarter, the sources said.But talks dragged on for more..