Gonzalo Higuain and Federico Fernandez have been called to Alejandro Sabella's provisional roster for Argentina, and it would take injury or an act of god for either to not make the final 23 man roster. Higuain has been amazing in his first season with Napoli, scoring 24 all-competitions goals to lead the squad in scoring in his first season away from Real Madrid. He'll almost certainly be starting up top in Brazil alongside Lionel Messi.
Fernandez has been an Argentina regular in recent seasons, and after easily the best club season he's ever had, he was a lock to make the squad this time. I'd be surprised if he isn't a starter in Brazil, and the chance has been very, very well-earned.
Elsewhere, Camilo Zuniga has been called in to Jose Peckerman's provisional Colombia squad, and Federico Fernandez has been named to Argentina's roster. Zuniga's season was largely wasted by a knee injury that took far, far longer to heal than first anticipated. He has, however, been on the bench in recent weeks and made a 20-minute substitute appearance against Sampdoria this past weekend, getting on the field for the first time since October. He has 50 caps for Colombia, so his inclusion is hardly a surprise, and he'll certainly play a role if he can get healthy enough.
Also, as expected, Miguel Britos was not called up Uruguay's provisional roster, with Oscar Tabarez electing to give Liverpool's Sebastian Coates a chance to win a job as he returns from injury instead.
Two Napoli players away on loan have also been named to World Cup squads: Pablo Armero (Colombia) and Eduardo Vargas (Chile). Armero is a bit of a shock, as he was extremely poor for Napoli in the first half of the season, then only managed to play five times for West Ham after being loaned to the English side in January. Edu Vargas hasn't really been a part of Napoli for over a year after Walter Mazzarri banished him on a loan to Brazil, but his loan with Valencia has been extremely productive, scoring five times in 24 league and Europa matches.