Part objects in Kleinian model

The following text is from Art and Psychoanalysis by Maria Walsh. It says that breast, milk, penis, children, and womb are part objects in Kleinian model. Are "children" really part objects in Kleinian model or have I got it wrong?

Text:

More importantly, the Kleinian symbolic universe offers a much welcomed alternative to the Freudian model of castration as being the bedrock of sexual identity. In a Kleinian model, ‘The first object of aggression is not, as it is in the Oedipal-centred Freudian model, the father, and not even the mother, but a series of part objects – breast, milk, penis, children, womb – to which the infant fantasises the connection of other part objects – mouth, teeth, urine, faeces – in frenzied attacks enacting, according to Klein, the force of the death drive.’