Back row Collins started the EDF Energy Cup victory over Northampton Saints at Franklin's Gardens in September and European Challenge Cup game with Clermont in October. He has also made a number of impressive Guinness 'A' league appearances.
Lock Bowley, who has represented England at U18, U19 and U21 level, has been handed three starts in the Europe, scoring a try in home victory over Albi in December, and also featured in the Guinness Premiership draw with London Wasps in late January.
John Brain, Worcester Warriors Director of Rugby, said: "Will and James have come through our Academy system. They've taken their opportunities well this season and have developed their respective games really well.
"This is further evidence that our policy of developing our own players at Worcester is now really paying dividends. I'm very pleased they are staying with us."