Cardiff midfielder Medel, who often plays as one of three centre-backs for his country, is included in manager Jorge Sampaoli's defensive options alongside Nottingham Forest's Jara.
Wigan midfielder Beausejour, who suffered Championship play-off heartache in the semi-final defeat by QPR, is one of 12 midfielders selected.
Juventus star Arturo Vidal has been named in the squad despite facing a race against time to prove his fitness after undergoing knee surgery last week.
Chile open their Group B campaign against Australia on June 13 and then face World Cup holders Spain and the 2010 beaten finalists Holland.
Chile provisional squad
Goalkeepers: Claudio Bravo (Real Sociedad) Johnny Herrera (Universidad de Chile), Cristopher Toselli (Universidad Catolica), Paulo Garces (O'Higgins)
Defenders: Gary Medel (Cardiff City), Jose Rojas (Universidad de Chile), Eugenio Mena (Santos, Brazil), Gonzalo Jara (Nottingham Forest), Marcos González (Union Espanola), Enzo Andia (Universidad Catolica).
Midfielders: Arturo Vidal (Juventus), Mauricio Isla (Juventus), Marcelo Diaz (Basel), Francisco Silva (Osasuna), Rodrigo Millar (Atlas), Pedro Pablo Hernandez (O'Higgins), Felipe Gutiérrez (Twente), Jose Pedro Fuenzalida (Colo Colo), Carlos Carmona (Atalanta), Jean Beausejour (Wigan), Charles Aranguiz (Internacional), Miiko Albornoz (Malmo).
Forwards: Alexis Sanchez (Barcelona), Eduardo Vargas (Valencia), Jorge Valdivia (Palmeiras), Mauricio Pinilla (Cagliari), Esteban Paredes (Colo Colo), Fabian Orellana (Celta Vigo), Matias Fernandez (Fiorentina), Gustavo Canales (Union Espanola).