Metcalfe, 18, is the younger sister of Wales full-back Nel Metcalfe and one of two pairs of sisters, along with prop Gwenllian Pyrs and lock Alaw Pyrs, to be selected in the squad. All four players began their playing careers at Clwb Rygbi Nant Conwy.
Wales hooker Carys Phillips is set to play in her fourth World Cup, while it will be a third outing for Hannah Jones, Jasmine Joyce-Butchers, Lleucu George, Kelsey Jones, Keira Bevan and Gwenllian Pyrs.
It will be a first major tournament experience for Seren Lockwood, Katherine Baverstock and Tilly Vucaj, who all won their first caps in Australia.
Carys Cox, Courtney Keight, Alaw Pyrs, Maisie Davies, Molly Reardon, Nel Metcalfe, Jenni Scoble, Catherine Richards, Bryonie King and Meg Davies will also make their World Cup debuts.
There is no place in the squad for Natalia John, Hannah Bluck, Jenny Hesketh, Sian Jones or Robyn Wilkins, some due to injury.
