Fell, Livingston, Woodbridge and Weale spearhead the GB challenge
Great Britain's modern pentathlon boss Jan Bartu is expecting the team to win a World Championship medal on home turf at Crystal Palace from 13-17 August.
Teenager Freyja Prentice replaces Louise Helyer in the women's team that won European team gold in June.
Olympic silver medallist Heather Fell won individual silver in Leipzig.
"We exceeded our expectations at the European Championships. We are definitely contenders in both genders," said Bartu, GB performance director.
"The World Championships are the pinnacle of the year, particularly for us as we will be at home.
"There will definitely be teams that are stronger than us but that will inspire us. Being at home means a medal is expected of us."
Katy Livingston and Mhairi Spence, who finished 10th and 12th at the European Championships, join Fell and Prentice in the women's team.
Beijing 2008 Olympians Sam Weale and Nick Woodbridge lead the men's challenge. Two further athletes will be added to the men's team nearer to the championships.
Prentice, 18, finished 10th on her World Cup debut in Mexico City in March.
On Monday, she helped GB into the final at the World Junior Championships in Chinese Taipei, along with Katy Burke, Charlotte Grandfield and Lydia Rosling.
GB team for World Championships:
Women: Heather Fell, Mhairi Spence, Freyja Prentice, Katy Livingston
Men: Sam Weale, Nick Woodbridge (two more to be added later)