A good performance by the Azzurri and a great response from the players who recently arrived after an extended holiday due to international duties this summer.
Osimhen scored the opening goal and then Napoli doubled the lead from the penalty spot.
Eljif Elmas, who gave a great performance in the last test before the new season, was tripped in the area and Insigne made no mistakes from the spot.
Spalletti has won six out of six games in charge of the Azzurri, ready to start the campaign against newly promoted Venezia on August 22.
Napoli 4-0 Pescara
Osimhen 9, Insigne 18, Ounas 47, Zedadka 77
Napoli (4-3-3): Meret (46′ Ospina); Di Lorenzo (64′ Zanoli), Rrahmani, Koulibaly, Mario Rui (46′ Malcuit); Lobotka (46′ Gaetano), Fabian Ruiz (64′ Palmiero), Elmas (77′ Zedadka); Politano (46′ Ounas), Osimhen (64′ Petagna), Insigne (77′ Machach)
Pescara (3-4-3): Radaelli (46′ Sorrentino); Cancellotti, Drudi (84′ Valdifiori), Frascatore (58′ Veroli); Zappella, Memushaj (68′ Longobardi), Pompetti, Nzita (58′ Rasi) ; D’Ursi, Marilungo (46′ Chiarella), Milos