Pescara goalkeeper Ivan Pelizzoli tried to provide some resistance for Serie A's bottom club, but once the first goal was scored by Gokhan Inler in the 46th minute, there was no looking back for Napoli.
Goran Pandev and Blerim Dzemaili added further goals to prevent Juventus from being able to celebrate winning the Scudetto later this weekend, and leave Pescara eight points from safety with four games of the season to go.
Udinese moved up to fifth with its fourth win in a row thanks to Roberto Pereyra's goal which sealed a 1-0 win against Cagliari.
Pereyra, who hit the crossbar in the first half, made amends with a more difficult effort midway through the second half to lift Udinese into a qualifying berth for the UEFA Europa League, ahead of the remainder of the weekend's matches.
Atalanta and Bologna drew 1-1 to both get the point they were looking for in a low-key affair at the Stadio Atleti Azzurri d'Italia.
Luigi Giorgi gave Atlanta the lead midway through the second period, but Alberto Gilardino equalised and the game returned to its first-half rhythm, with both teams seemingly content to settle for a draw.