。
She insisted that she would go there.
Literal
She [topic-は] there [to-に] go [quotative-と] insisted.
主張する ('to claim/assert/insist') is stronger than 言う — it implies pushing one's position, not just stating it. The と is the quotative particle marking the embedded clause そこに行く ('she will go there') as the content of the assertion. Note that the embedded verb stays in plain form and present tense regardless of the matrix verb's tense — Japanese doesn't shift embedded tense the way English does. The natural English 'she would go' reflects English's backshifting; the Japanese sticks with 行く ('go', present/future).